Mr O-Ring 373 Viton O-Ring 90A Durometer, 9 in ID - Pack of 5

In this review the focus is a practical, industrial-grade sealing option for engineers, mechanics and maintenance techs who need reliable resistance to fuels, oils and heat. The Mr O-Ring 373 Viton o-ring is a 90A durometer Fluorocarbon rubber designed for demanding environments; the single biggest reason to consider it is its compatibility with petroleum products and wide temperature range, which makes it useful where other elastomers fail. This pack of five offers spares for routine maintenance and reduces downtime when matched to the right AS568 size.

Key Features

• Material: Viton FKM composition delivers excellent resistance to fuels, mineral oil and many organic solvents for longer seal life.
• Durometer: 90A hardness provides a firm cross-section that holds shape under pressure while maintaining a reliable seal in many systems.
• Temperature range: Rated -26C to 232C (-15F to 450F), allowing use in both cold starts and very hot service conditions.
• Size accuracy: Nominal and actual dimensions are listed, so users can match this o-ring to AS568 size equivalents with confidence.
• Pack quantity: Supplied in a pack of 5 to keep spares on hand for routine replacement without buying bulk quantities.

Who It's For

The o-ring is ideal for technicians and maintenance teams working on fuel systems, hydraulic equipment or any application exposed to petroleum, diesel, or high temperatures who need a compact, dependable seal that meets common size standards. Contractors who service engines, pumps or industrial valves will appreciate the Viton compatibility with aromatics, strong acids and silicone oils.

It is less suited for users who need very soft, low-durometer seals for light compression applications or where food-grade compliance is mandatory; those users should choose a different material or hardness. Also, if metric-only specs are required, confirm dimensions carefully against the provided metric values.

Pros & Cons

Pros

• Excellent chemical resistance to fuels, oils and many solvents, making it durable in harsh fluids.
• High temperature capability to 232C (450F) supports hot-system use without rapid degradation.
• AS568-compatible dimensions and clearly stated actual measurements help ensure the right fit.
• Pack of five provides convenient spares for scheduled maintenance and repairs.

Cons

• At 90A durometer the o-ring is relatively firm and may not be ideal where very soft sealing compression is required.
• Not intended for applications requiring food-grade elastomers or extreme low-temperature flexibility below -26C.

Specifications

Our Verdict

The Mr O-Ring 373 Viton 90A o-ring is a solid choice for industrial and mechanical users who need a compact, high-temperature resistant seal compatible with petroleum and many chemicals. It offers clear sizing, reliable chemical resistance and a pack size useful for maintenance crews; those needing very soft seals or food-safe materials should consider alternatives.

Frequently Asked Questions

Is this o-ring compatible with gasoline and diesel?
Yes, the Viton FKM formulation is rated for petroleum products including gasoline and diesel, as well as biodiesel blends.

What are the actual dimensions versus nominal?
The listing provides both: actual dimensions are 8.975 in ID, 9.395 in OD, 0.210 in cross-section while nominal is 9 in ID, 9-3/8 in OD, 3/16 in CS.

Can it be used at very high temperatures?
Yes, the service range goes up to 232C (450F), suitable for many high-temperature applications.